Question detail
What is the purpose of the salt bridge in an electrochemical cell?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Electrode potentials and electrochemical cells (A-level only)
Question
- A. To maintain electrical neutrality by allowing ions to flow between the half-cells.
- B. To provide a source of electrons.
- C. To increase the voltage of the cell.
- D. To prevent the mixing of the two solutions.
Answer
To maintain electrical neutrality by allowing ions to flow between the half-cells.
Explanation
The correct option is To maintain electrical neutrality by allowing ions to flow between the half-cells.. To maintain electrical neutrality by allowing ions to flow between the half-cells. is the best answer because it directly supports the AQA A-Level Chemistry objective to predict the feasibility of redox reactions using electrode potentials. This reasoning is anchored to Feasibility and applications of cells (A-level only) in Electrode potentials and electrochemical cells (A-level only), and it separates electrode potential from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Misunderstanding Electrode Potential Calculation
Students often confuse the standard electrode potential values and fail to apply the correct signs when calculating cell potentials.
To predict the feasibility of redox reactions using electrode potentials, use the formula: E_cell = E_cathode - E_anode. Substitute the correct standard electrode potentials for the cathode and anode, ensuring to maintain the correct signs. For example, if E_cathode = +0.76 V and E_anode = -0.44 V, then E_cell = 0.76 - (-0.44) = 0.76 + 0.44 = 1.20 V. Thus, the cell potential is 1.20 V, indicating the reaction is feasible. Keep the correction anchored to Feasibility and applications of cells (A-level only) and the objective: Predict the feasibility of redox reactions using electrode potentials.
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